Custom call IC-s for String.prototype.{charAt,charCodeAt}.

src/objects.h

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
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 const uint32_t kAsciiStringTag = 0x4;
 
 // If bit 7 is clear, the low-order 2 bits indicate the representation
 // of the string.
 const uint32_t kStringRepresentationMask = 0x03;
 enum StringRepresentationTag {
   kSeqStringTag = 0x0,
   kConsStringTag = 0x1,
   kExternalStringTag = 0x3
 };
+const uint32_t kIsConsStringMask = 0x1;
 
 
 // A ConsString with an empty string as the right side is a candidate
 // for being shortcut by the garbage collector unless it is a
 // symbol. It's not common to have non-flat symbols, so we do not
 // shortcut them thereby avoiding turning symbols into strings. See
 // heap.cc and mark-compact.cc.
 const uint32_t kShortcutTypeMask =
     kIsNotStringMask |
     kIsSymbolMask |
@@ skipping 4828 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_